4-4,,,,,
Passenger-Miles,,,,,
(Millions),,,,,
Mode,1970,1980,1990,2000,2004
Air,,,,,
Air carrier,"108,442","204,368","345,873","516,129","557,893 "
General aviation,"9,100","14,700","13,000","15,200",U
Highway,,,,,
Passenger cars,"1,750,897","2,011,989","2,281,391","2,544,457","2,693,872"
"Other 2-axle, 4-tire vehiclesa","225,613","520,774","999,754","1,467,664","1,758,542"
Busesb,N,N,"121,398","160,919","140,716"
Motorcycles,"3,277","12,257","12,424","11,516","12,761"
Rail,,,,,
   Transitc,N,"10,939","12,046","15,200","P15,930"
   Commuter,"4,592","6,516","7,082","9,402","P9,719"
   Intercity/Amtrakd,"6,179","4,503","6,057","5,498","5,511"
Other transite,N,390,841,"1,631","P1,874"
"a Includes vans, pickup trucks, sport utility vehicles, and other 2-axle, 4-tire motor vehicles that are not passenger cars.",,,,,
"b Includes municipally owned transit and commercial, federal, and school buses.",,,,,
c Includes light and heavy rail only.,,,,,
d Fiscal year data.  Amtrak began operations in 1971.,,,,,
"e Includes demand response, ferryboat, and other transit not specified; 1980 data include ferryboat and “other transit” only.",,,,,
Key: N = data are nonexistent; P = preliminary; U = unavailable.,,,,,
"Sources: Various sources, as cited in U.S. Department of Transportation, Research and Innovative Technology Administration, Bureau of Transportation Statistics, National Transportation Statistics, table 1-37, available at http://www.bts.gov, as of September 2006.",,,,,